The invention relates to a contactor apparatus comprising an electromagnet controlling power contacts and having means for automatically opening these power contacts each of which responds, on the one hand, to the appearance of short circuit currents in one of the power circuits through a coil and a striker and, on the other hand, to the appearance of overload currents either instantaneous or of a longer duration through a coil associated with a plate and, respectively with a bimetallic strip, each power contact being adapted to cooperate, after striking, with a locking member which holds it in the open position, this apparatus having a local member adapted to reset the automatic opening means and to close again a control switch placed in series with the coil of the electromagnet.
Such contactors, which are intended for ensuring simultaneously the power supply of consumer apparatus and the rapid protection thereof as well as that of the lines which feed them, avoid the series connection of two apparatus each having a system of switches one of which carries out the on and off operation while the other ensures the protection; it is in fact known that such an association between two systems of switches requires a coordination which it is difficult to obtain because of the radically different properties which are required not only insofar as their closing powers are concerned, but also their opening speeds. This coordination is all the more delicate to achieve since each of these types of switches may be offered to the public by different suppliers and since their properties are not always known by the users.